- February 9, 2017
In the spring and summer, when bugs are buzzing and plants are blooming, a bird’s diet will most likely consist of a variety of abundant, protein-rich insects. In northern regions where warm seasons change to cold, those insects become fewer and harder to find, convincing many avian species to migrate to tropical locations where insects are found year-round, or to change-up their primary food source–relying not on insects, but on winter berries. Read on to learn about putting this valuable habitat feature to work.
Migratory neotropical songbirds are usually insectivorous and are among many who make the long journey between North and South America to feed almost exclusively on insects and other invertebrates, like worms. Many warblers, like the Common Yellow-throat shown above, will migrate to North America during breeding season to take advantage of the abundant insect foods that appear in the spring and summer and return south as those food sources dwindle. They almost never eat food from plants, which is one reason you won’t see them at your feeders.
On the other hand, many songbirds are year-round residents and will stay in northern latitudes even during the coldest winter months. They are able to eat a larger diversity of foods as the seasons change, including berries, seeds, and nuts, that are available from native shrubs and trees. The image above, taken in November, shows an American Robin in Ontario, Canada investigating some Mountain-Ash berries, still lingering from when they ripened in early autumn. Year-round residents rely on persistent berries, like these, to sustain them through the winter season.
In the spring and summer, this same robin will be found gorging on insects, like caterpillars in the image above, as soon as this food source becomes available. Research has even suggested that these seasonal shifts in food abundance help cue physiological changes that prepare birds for breeding seasonopen_in_new. A landscape with berry-producing native trees and shrubs provides the resources that support these seasonal cues by producing high-fat berries in the fall and attracting insect food in the spring.
Berries are not eaten by winter residents alone, they are also an important food source for fall migrants. The journey between breeding and wintering grounds is very energy-intensive for songbirds, who have built up immense fat stores in anticipation only to completely exhaust them along the wayopen_in_new. Small migrants are particularly vulnerable during migration because they cannot store enough fat to sustain their entire journey, and must rely on stopover sites to rest and replenish their body fat.
Habitats that support abundant fruit resources are likely to represent high-quality stopover sites for refueling birds during their migrationopen_in_new. The Yellow-rumped Warbler above is feasting on poison ivy berries during its southward migration. Though many gardeners consider this native shrubby vine a nuisance plant, poison ivy (Toxicodendron radicans) produces just the kind of fat-rich berries that are essential for sustaining migrating birds during fall and year-round residents in the winter.
Different berries have different nutritional content profiles. The amount of sugar, fat (lipids) and fiber contained in a berry vary by plant species. Some berry-producing shrubs fruit earlier in the season, some later, while still others persist deeper into the winter months when food is especially scarce (like the Ilex verticillata in the image to the right). There is a lot of natural variation in fruit availability and the birds that have evolved with this seasonal fruit diversity depend on it for energy resources all year round.
One way to handle this complexity is to embrace it and plant a broad diversity of berry-producing shrubs and vines that provide a variety of fruits at different times. You’ll want something with fruits in the late summer, fall, and early winter. Many year-round residents, like the Black-capped Chickadee to the left, will readily switch to a plant-based diet as the months turn colder and the insect populations dwindle. Shrubs and trees native to the area will have their seeds and berries ready when the birds are looking for new food sources (because they have evolved to do so in a delicately timed ecological dance). Exotic plants are not as likely to be seasonally in-sync with the resources that birds need and native plants can provide.
Landscape designers often use something called a planting palette (see the one above) to ensure a variety of colors and bloom times throughout the seasons in the gardens they are planning. Our friends in the Department of Landscape Architecture at Cornell repurposed this concept to create planting palettes that also take into account fruiting times. You can see one above designed for a suburban yard in the Northeast.
This plant palette example shows the resources that are available from each native plant at various times of the year during key life events for birds. Often the same shrubs or trees that can provide shelter for nesting birds can later provide fruit in the winter and attract insects in the spring. This palette is based on observed bird activity and native plants that are available for home gardens. It matches the seasonal timing of specific bird’s habitat requirements and includes quantities and abundances for average monthly bird sightings.Download Palette
You can construct your own planting palette using your local native plants database, which we link to in our local resources tool. The tool takes your zip code and connects you directly to your state’s native plant resources. Once there you can access a wealth of local native plant, pollinator, and birding information. You will be provided with a map showing your local plant hardiness zone as well as your local ecoregion. Also provided is a planting guide to direct you towards native plant selections that support birds, pollinators, and other wildlife.
Under the map is a collection of gardening and habitat improvement resources including a list of local native plant nurseries near your home. To help you select the ideal plants for the spaces you have to fill, choose the item labeled Your State’s Native Plants. This will take you to the Lady Bird Johnson Wildflower Center website and will automatically load a selection of native vegetation for your area. You can filter the list to find that perfect berry-producing plant for the perfect time of year. Use the filter choices in the left sidebar to choose soil and light requirements or height and color preferences to find the ideal plants for your palette.